Oil Consumption-I need to know your thoughts

[BMFH]

Oil in PCV

Hello All

The oil distrubation plate covers a cavity on the block where the dummy cam blank or shaft for the oil pump drive rotates, it is pretty much a sealed cavity in that the crankshaft windage and the slung off oil does not have a direct path to the PCV oil seperation baffel that is under the plate.

Exess blow-by form tired piston rings may be forcing heavy oil ladend vapor to be sucked past the PCV oil seperation baffel under the plate and thru the PCV valve and into the intake manifold.

Maybe you could do a leak down test to see if the rings are in good shape and not by-passing too much compression. A leak down test is much better than a compression test in that it uses a regulated and metered CFM volume of air to pressurize the combustion chamber with all 4 valves closed and the piston at TDC for the cylinder being checked, (Kind of hard to do sometimes)

PLEASE, PLEASE, WATCH OUT FOR YOUR FINGERS, HANDS, ETC.

THE ENGINE "WILL ROTATE/TURN OVER" IF THE PISTON BEING CHECKED IS NOT AT "TDC" WHEN THE 100 PSI OF AIR PRESSURE IS APPLIED TO THE CYLINDER.

It gives a percentage of leakdown (gage reading) of air pressure or volume lost past the rings, or valves, you can tell where the leakage is by listening to the oil filler cap hole for ring leakage, the intake manifold open throttle body for intake valve leakage or the tail pipes for exhaust valve leakage. Sometimes a 3-4 foot piece of heater hose can be held to your ear to amplify the sound of the air that is escaping.

I have talked on the forum about the oil seperating catch can before, but there is hardly any place to put it and be able to route a drain line so that the oil can drain back to the oil pan area. It sure would stop the oil in the intake problems, except on an really tired engine with an awful lot of excessive blow-by.

Another problem of using the catch can is that it would have to have a fairly large capacity for long trips and it is also effected by engine manifold vacuum. It would have to have some type of check valve that would open and allow the captured oil in the catch can to gravity drain back to the oil pan after engine shut-down.

Hope this helps

John

[denial]

BMFH,
Thanks for the great info. I figured my compression test was a sure thing for knowing if my rings are shot. I'll probably take it in for the leak down test. I don't have the tools and I'm not going out and buying all that just for this. Where was my oil-laden vapor going when I had the PCV re-routed? Also, if you have excess blow by and don't have the crankcase vented with the vacuum through the PCV will you get fuel in the oil? (oil level would rise. Mine seemed to go up a little bit when the PCV was not connected to the plenum, unless the level was inconsistent for me.)
I have spent many hours thinking about how I could design an oil catch for it, but like you said, there's quite a few hurdles to get over and I don't want to keep driving the car if it's tired. I'd just as soon get it re-ringed. Hmmmmmmmmm.........convert the windshield wash fluid tank into one........hahaha!!! Kidding!

[BMFH]

denial and all

Not sure what the PCV line would have on fuel being in the oil, Nothing I can think of at the moment.

You may have a problem with one or more fuel injectors leaking down and bleeding off the fuel rail residual line pressure after engine shutdown, leaking into the cylinders, draining past the rings, and into the pan and contaminating the oil and raising the oil level in the pan. This will cause the rings and cylinder walls to be void of oil and lubrication, causing premature wear of the rings and cylinder walls at start up (Dry Start)

Another possibility is the fuel pressure regulator diaphram. It could have a small hole in it that is allowing the residual fuel line pressure to bleed off and into the intake manifold thru the vacuum line that goes from the intake manifold to the fuel pressure regulator. From the intake manifold it is a short trip to the oil pan, same as the injectors leaking down.

Another indication of lost fuel pressure is when you first go to start the engine after setting overnight or for an extended period of time, if it cranks for awhile before starting then it has probably lost the residual line pressure. The engine should start right up as soon as it cranks and turns a couple of revolutions for the comptuer to see the crank position sensor and cam sensor if installed.

You can check this pressure by installing a fuel pressure test gage on the fuel rail test port and starting the engine,

BE VERY CAREFUL NOT TO SPRAY ANY GASOLINE ON THE ENGINE WHEN CONNECTING OR REMOVING THE FUEL PRESSURE TEST GAGE, "EXTREME FIRE HAZARD", CATCH GAS IN A RAG AND REMOVE ALL RAW GASOLINE AND RAGS FROM THE ENGINE BEFORE STARTING IT.

Notice the fuel pressure reading (approx. 35-45 PSI), shut down the engine and monitor the pressure reading, it should stay at that pressure for many hours/overnight. If it doesn't, then the fuel injectors or the fuel pressure regulator are bleeding off the fuel rail residual pressure.

The check valve on the in tank fuel pump can also bleed off the fuel system residual line pressure, but it won't have any effect on the fuel getting into the engine oil.

If you listen closley when you turn on the ignition switch, you can hear the in tank fuel pump power up for a second or so to boost the line pressrue in the fuel system/fuel rails, if the fuel filter is really clogged there may be a delay in the pressure building up promptly, a clogged filter can also cause a hard starting engine, and drivability problems too.

Hope this helps too

John

[denial]

John,
My engine pops right off when starting, so I believe I'm good in this department. I probably took a stab in the dark on that last post and should have kept that one to myself. I probably had an inconsistant dipstick reading and just "thought" my oil level went up.

Does the oil distribution plate have pressurized oil anywhere in it or around it? Possibly for lubrication of the dummy cam blank?

denial

[BMFH]

Oil Dristribution Plate

Hello Denial and All

The oil dristribution plate routes oil from the engine block to each Cylinder head thru dual anti drain back check valves, (one for each bank) up to the cam box's thru internal driled passages.

Any time you are doing the lower intake manifold I think that it is very important and wise to replace the oil dristribution plate gasket , it gets hard and cracks and then leaks, you don't want to have go in there a second time to repair another oil leak, might as well replace it and do some PM at the same time, the old gasket is really stuck on good, be carefull not to gouge the gasket mating surfaces because the gasket may not seal properly and you will still have an oil leak. One extra gasket is cheap insurance compaired to another upper and lower gasket set. Also make sure the plate is flat and not warped, or it will not seal properly on the gasket. Its is Very Important not to let the gasket debris get down into the engine inside the cavity under the distribution plate, do not use the 3M pads with a sander to clean off the gasket.

When I worked at Ford they lost a bunch of engines because the guys were using the 3M pads and wern't very carefull, and let the gasket debris get into the engines and clogged things up.

The PCV Valve ("P"ositive "C"rankcase "V"entalation) and its purpose:

The PCV Valve was installed on engines many many years ago, the engines prior to the PCV valve installation had an overboard vent tube (Road Draft Tube) its job was to help vent all vapor, pressure and blowby produced by the engine to the atmosphere on the outside of the engine.

If you will notice in the Exhaust when the engine is cold you can see water vapor in the exhaust discharged untill the engine and all the metal parts get warmed up. All metal Sweats when heated and creates moisture that coats the metal when this heat is applied.

The same thing happens on the inside of the engine when the heat of the compustion process is applied to the metal, The inside of the engine sweats profusly, this moisture condenses and mixes with the engine oil an forms off white Milky Looking Sludge and some Rust. It usualy accumulates in areas of the engine where it does not get enough oil flow of splash to knock it loose, I.E. behind the timing chain cover, inside the valve covers, top side of the heads, in the valley for the cam and lifters, even the road draft tube itself, Etc. Etc.

When they first started working on SMOG problems on cars, one of the things they did was to install a PCV valve to prevent the all the vapors from escaping the engine via the road draft tube and being discharged into the atmosphere. That was a Good Thing, what it also does is draws fresh air into and all through the inside of the engine, drawing the sweating moisture and oil vapors into the intake manifold and burning them in the combustion process. If you will notice on like a V8, the fresh air goes in from the air cleaner to one valve cover and out the PCV valve on the other valve cover and into the intake manifold to be burned, this forces air to be drawn completly though the entire engine and prevents the Milky Sludge and Rust from forming in the first place.

In the days of the Road Draft Tubes, engines were completly worn out by the 100,000 mile reading on the odometer. The oils of the day didn't help much either, they were all "NON DETERGENT" Parifin Ladened and Re-clamed/re-refined oils that put a BLACK waxy coating on all internal engine parts, I have seen it 1/2" thick inside of engines that were not taken care of. The 100,000 mile stigma is still with us today, in that a lot of people think that everything is worn out by then, NOT!, they are just starting to get broken in at 100,000 miles these days. We have our own 200,000 Mile club on this Forum as proof.

Today with the PCV valve, and much better oils, it's nothing to see engines go 200,000 miles and much more and still be going strong.

Diesel Road Haul Trucks go 500,000 miles before a major overhaul is even considered, and they will go through 4 major overhauls before the owner will concider replacing the Truck.

So I guess you can say, "WE HAVE COME A LONG WAY"

Take Care, sorry this got so long, hope it helps.

John

[SappySE107]

RE: Oil Dristribution Plate

Great info We could use info like that on the site!

[jcollins]

Excessive Oil Consumption

Gm released technical service bulletin no 67-60-01 in february 1997,this bulletin relates to the excess oil consumption of the 3.4 DOHC engines from 1991-1995.Bottom line is if all checks good on these engines their fix was to replace the fresh and foul air sides of the PVC system.
Their procedure is listed below

1. Remove the fuel injection sight shield.
2. Remove the front spark plug wires.
3. Remove the front cam cover and replace with new cover, P/N 24505197. Tighten bolts to 11 N.m (97 lb in.).
4. Install new oil fill cap, P/N 12551958.
5. Remove the PCV system emission harness and install new harness, P/N 24507504.
6. Install new PCV valve, P/N 25095452. On 1991-93 vehicles, remove PCV hose at upper manifold inlet and replace with P/N 24503122.
7. Install new spark plug wires and reuse the wire retainer clip for cylinders 2-4-6. Remove the spark plug wire retainer clip from the metal bracket and reuse just the clip portion.
8. Reinstall the fuel injector sight shield.
Parts are currently available from GMSPO.